Fuel pump

ABSTRACT

A fluid pump having a housing with an inlet and an outlet, and provided with a pair of cam tracks in a side by side relationship. A vane carrying rotor is rotatably mounted within the cam tracks, a portion of the vanes carried by the rotor engaging one track and forming a first pumping means connected to the inlet of the device; the remaining vanes carried by the rotor engaging the other cam track to form a second pumping means connected intermediate the first pumping means and the outlet of the device, whereby a single flow path is defined through both pumping means of the device. A pressure regulator is connected intermediate the pumping means and takes the form of an aneroid operable to maintain a constant pressure at the inlet of the second pumping means and to open at a predetermined pressure value to return a portion of the fluid to the inlet of the device.

[is] 3,680,980 [451 .Aug. 1,1972

FUEL PUMP [72] Inventor: Hans U. Bart, 5820 Duck Lake Road, Whitehall,Mich. 49461 221 Filed: Feb.20, 1970 21 App1.No.: 12,965

[52] US. Cl. ..417/253, 417/310, 418/13, 418/212 [51] Int. Cl......F04b49/00, F04c 1 1/00, F04c 13/00 [58] Field ofSearch ..418/13,210,2l5,253, 254, 418/255;417/251,252, 253,310;

[56] References Cited UNITED STATES PATENTS 2,533,047 12/1950 Robinsonet a1. ..417/252 1,586,806 6/1926 l-lohagen ..418/212 2,917,067 12/1959Pearl ..60/39.28 T 2,108,771 2/1938 Laird ..417/252 2,410,774 11/1946Chandler ..123/139.l2 899,040 9/1908 Gill ..418/255 2,824,687 2/1958Osterkamp ..418/13 2,009,137 7/1935 Kleckner ..417/252 2,381,695 8/1945Sennet ..417/311 X 2,165,963 7/1939 Curtis ..418/255 PrimaryExamiherCarlton R. Croyle Assistant Examiner-John J VrablikAttorney-Hauke, Gifford and Patalidis 5 7 ABSTRACT A fluid pump having ahousing with an inlet and an outlet, and provided with a pair of camtracks in a side by side relationship. A vane carrying rotor isrotatably mounted within the cam tracks, a portion of the vanes carriedby the rotor engaging one track and forming a first pumping meansconnected to the inlet of the device; the remaining vanes carried by therotor engaging the other cam track to form a second pumping meansconnected intermediate the first pumping means and the outlet of thedevice, whereby a single flow path is defined through both pumping meansof the device. A pressure regulator is connected intermediate thepumping means and takes the form of an aneroid operable to maintain aconstant pressure at the inlet of the second pumping means and to openat a predetermined pressure value to return a portion of the fluid tothe inlet of the device. I

11 Claims, 5 Drawing Figures FUEL PUMP BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates to fluid pumps, and

more particularly to an improvement in sliding vane type pumps andmotors.

2. Description of the Prior Art The related prior art devices take theform of a pump utilizing a rotor having a plurality of spaced radialvanes rotatable therewith and slidable relative thereto in slotsprovided in the rotor. The rotor and vanes cooperate with a vane trackin the stator member which defines fluid inlet and fluid outlet zonesbetween the outer periphery of the rotor and the vane track and throughwhich the vanes pass carrying fluid from the occupied by the vaporunless it is eliminated at least to some extent the volume of fueldelivered to the engine will not be sufficient to sustain it and this,of course, can'result in the engine stalling.

SUMMARY OF THE INVENTION The pump of the present invention includes dualpumping chambers in which the vanes associated with the two chambers arecarried by a common rotor, the outlet of the first pumping chamber beingconnected to the inlet of the second pumping chamber such that the fuelpasses through the two pumping chambers in a series type connection. Thecapacity of the first pumping means is greater than that of the secondpumping means and is designed to deliver more fuel than will benecessary to operate the engine. A pressure responsive valve is disposedintermediate the pumping chambers and performs a dual function. First,the valve opens to return the excess fuel from the first pumping chamberoutlet to the inlet of the device and, secondly, the valve is operableto maintain a predetermined constant pressure between the outlet of thefirst pumping means and the inlet of the second pumping means.

By providing an arrangement by which the first pumping means deliversmore fuel than required and by which the excess fuel is delivered backto the inlet of the device, the vapor problem is substantially reduced.There will be sufficient liquid fuel delivered to the inlet of thesecond pumping means even when vapor occupies a part of the volume ofthe fuel delivered to the first pumping means. The pressure regulatingmeans is designed to maintain a sufficient pressure at the inlet of thesecond pumping means to insure that all fuel delivered to the secondpumping means will be in liquid form. An added result of the pressureregulating means is that pressure surges in the system will beeliminated and the effect of both of these results is that the secondpumping means can be designed to fulfill the required metering functionand can therefore be relied upon to provide the proper amount of fuel tothe engine under all operating conditions.

It is therefore an object of the present invention to substantiallyreduce the effects of fuel vaporization on the delivery of fuel to anengine by providing a fuel pump comprising a first pumping meansdesigned to deliver a quantity of fuel greater than that needed by theengine, a second pumping means receiving fuel from the first pumpingmeans and delivering the fuel to the engine and pressure regulatingmeans intermediate the first and second pumping means and operable toregulate the pressure of the fueldelivered to the inlet of the secondpumping means to a predetermined value and to return excess fuel fromthe outlet of the first pumping means to the inlet thereof.

It is also an object of the present invention to provide a fuel pumpcomprised of two pumping means and a pressure regulating means withinthe same housing by providing a rotor being associated with first andsecond pumping chambers and carrying vanes in each of the pumpingchambers, the first chamber being adapted to transfer fuel to the secondpumping .chamber such that the fuel entering the device travels along asingle path from the inlet to the outlet thereof and by providing apressure regulator carried by the housing and connected intermediate thepumping chambers.

Other objects, advantages and applications of the present invention willbecome apparent to those skilled in the art when the accompanyingdescription of one example of the best mode contemplated for practicingthe invention is read in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The description herein makes referenceto the accompanying drawing wherein like reference numerals refer tolike parts, and in which:

FIG. 1 is a longitudinal sectional view of a fluid pump embodying apreferred form of the present invention and taken on line 1-1 of FIG. 2;

FIG. 2 is a transverse sectional view taken on line 2 2 of FIG. 1;

FIG. 3 is a transverse sectional view taken on line 3- 3 of FIG. 1;

FIG. 4 is a diagrammatic representation of the flow part of fluidbetween the inlet and outlet passageways of the device illustrated inFIGS. 1, 2 and 3; and

FIG. 5 is an elevational view of the vane members shown in FIGS. 1, 2and 3 removed from the other members for purposes of clarity.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, andparticularly FIG. 1, there is shown a fluid pump 10 of a sliding vanetype. The device 10, preferably comprises a housing 12 having a waferplate 14 sandwiched between a body section 16 and an end cover 18, allof which are suitably connected to each other by bolts 19 extendingaxially through the housing 12. A bore 20 formed within the body section16 accommodates a pair of cam rings22, 24, which are separated by a wearplate 26. The cam rings 22, 24 are sandwiched between wear plates 27 and28 respectively disposed on the inner and outer ends of the bore 20.-

The body section 16 is provided with an inlet supply connection port 30having an inlet passage 32 terminating in a fluid opening 34. The fluidopening 34 extends through the cam ring 22 to the inner peripherythereof.

As can best be seen in FIG. 2, the end cover 18 is provided with anoutlet connection port 36, having an outlet passage 38 extending throughthe end cover 18, the wafer plate 14 and terminates in a fluid opening40 (FIG. 1) formed in the cam wear plate 28 which in turn opens to theinner periphery of the cam track 24.

A rotor 42 having an axial width which is slightly less than thecombined axial widths of the cam rings 22, 24 is sandwiched between thewear plates 27 and 28 and is rotatably mounted within the cam rings 22,24 by means of a drive shaft 44, which, in turn, is rotatably mountedwithin a sleeve bearing 46, mounted within the body section 16. A seal48 is provided to prevent leakage past the shaft 44 during operation.The seal 48 is maintained in place by means of a snap ring 50 which ispositioned within a groove 52 formed in the body section 16. I

A seal 54 prevents leakage at the juncture of the body section 16 andthe wafer plate 14, while a gasket 56 prevents leakage at the junctureof the end cover 18 and the wafer plate 14.

The rotor 42 is provided with a plurality of radial through slots 58(FIGS. 2 and 3). Each of the radial slots 58 accommodates a pair ofvanes 60 and 62, which are axially separated within the rotor 42 by anysuitable seal (not shown). The vanes 60 and 62 are substantially alikeand one of these is shown in elevation in FIG. 6. As can be seen in FIG.6, the vanes 60, 62 are provided with a medial side recess 63 whichreceives another similar vane at right angles to the vane shown topermit sliding movement of each of the vanes without interference witheach other. The vanes 60 and 62 are thus adapted to be slidably movablewithin the slots 58 such that their outer ends 64 and 66, respectively,contact and follow a pair of cam tracks 68, 70 respectively formed onthe inner periphery of the cam rings 22, 24. The last mentioned vaneseparating seal extends to the outer periphery of the rotor 42,whereupon it engages in a fluid sliding seal (not shown) tosubstantially prevent fluid communication between the space defined bythe peripheral surfaces of the rotor 42 and cam tracks 68, 70 onopposite sides of the wear plate 26.

Referring to FIG. 2, it can be seen that the cam track 68 formed on the.inner periphery of the cam ring 22 is in the form of a lamnicone whichis common in vane type pumps. The cam track contour and the outerperiphery of that portion of the rotor 42 associated with the cam track'68 define a working chamber indicated by the numeral 72, which forpurposes of convenience may be divided into a fluid inlet zone 74 and afluid outlet zone 76. The fluid inlet zone 74 is that portion of theworking chamber 72 which registers with the inlet fluid opening 34,which extends through the cam ring 22, while the fluid outlet zone 76 isthat portion of the working chamber 72 which registers with a fluidopening 78.

The fluid opening 78 communicates with a passageway 80 which extendsaxially through the body section 16 to a radial passageway 82, extendingthrough the wafer plate 14. The radial passageway 82 terminates in afluid opening 84. v

As the portion of the vanes 60 disposed in the radial slots 58associatedwith the cam ring 22, traverses the inlet zone 74 (in acounterclock-wise direction as viewed in FIG. 2), the vanes 60 willfollow the cam track 68 and will be moved radially outwardly therebywith respect to the rotor 42, while the opposite end of the vane 60 istraversing the fluid outlet zone 76 and therefore will be moved radiallyinwardly with respect to the rotor 42. As the vanes 60 move from theinlet zone 74 to the outlet zone 76 fluid is displaced from the fluidopening 34 to the fluid opening 78, into the axial passageway and radialpassageway 82 and into the fluid opening 84.

It should be noted that other means may be utilized to maintain thevanes 60 in an extended position with respect to the rotor 42 as thevane 60 traverse the cam track 68 during a cycle of the device. Forinstance, the vanes 60 could be of a two piece construction withcentrifugal force being relied upon to maintain contact between the endsof the vanes and the cam track. Other means could include acommunication of high pressure fluid to the underside of the vanes 60 oralternatively, springs could be disposed within the inner portion of theslots 58 to bias the vanes 60 outwardly into engagement with the vanetrack 68.

Referring now to FIG. 3, the inner surface of the cam ring 24 forms thecam track 70 which as previously indicated is lamnicone in shape. Theouter ends of the vane 62 are adapted to remain in contact with the camtrack 70 as the same rotates through a cycle in the same manner ashereinbefore described in the description of the operation of the vanes60. Like the vanes 60, the

vanes 62 could also be urged outwardly to engage the cam track 70 bymeans other than those utilized in the present construction. The camtrack 70 and the outer periphery of that portion of the rotor 42associated therewith defines a working chamber 86 which, for the purposeof convenience, may likewise be divided into a fluid inlet zone 88 and afluid outlet zone 90. The fluid inlet zone 88 is that portion of theworking chamber 86 registering with the fluid opening 84 while the fluidoutlet zone is that portion of the working chamber 86 registering withthe fluid opening 40. As the ends 66 of the vanes 62 traverse the fluidinlet zone 88, that portion of the vane 62 moves radially outwardly withrespect to the rotor 42 while the opposite end of the vane 62 istraversing the fluid outlet zone 90, and is therefore moving radiallyinwardly. As the vanes 62 traverse the cam track from'the fluid inletzone 88 to the fluid outlet zone 90, (in a clockwise direction as viewedin FIG. 3) fluid is displaced from the fluid opening 84 to the fluidopening 40.

Thus it can be seen that one section of the rotor 42, the vanes 60 andthe chamber 72 define a first pumping means, while a second section ofthe rotor 42, the vanes 62 and the chamber 86 define a second pumpingmeans. The pumping means are connected in series and are containedwithin the same housing 12. It should also be noted, and it is apparentfrom an examination of FIG. 1, that the section of the rotor 42 formingthe first pumping means is axially longer than the section forming thesecond pumping means. This means that the first pumping means has agreater pumping capacity than the second pumping means. In practice, ithas been preferred when using the pump as an aircraft fuel pump todimension these sections so that the first pumping means deliversapproximately twice the volume that the second pumping means is capableof delivering. Further in aircraft systems, the first pumping means isdesigned to deliver more liquid fuel than the aircraft engine willrequire under any operating conditions.

As can best be seen in FIGS. 1 and 4, a pressure regulating device 92 isprovided in a bore 94 formed in the end cover 18. A cover 96, closes thebore 94, while an O-ring 98 provides between the juncture of a cover 96and the end cover 18 insures fluid tightness. The pressure regulatingdevice 92 comprises an expansible-contractable fluid tight member whichin the preferred embodiment takes the form of an aneroid or bellows typemechanism 100.

As viewed in FIG. 1, the lower portion of the aneroid 100 is providedwith a valve member 102, which is slidably movable through a bore 104 ofdecreased diameter relative to the bore 94 and formed in a partition105. The valve member 102 is adapted to cooperate with a valve seat 106formed between an inlet 108 and an outlet 110 of the pressure regulatingdevice 92. The outlet 110 is connected to the inlet port 30 by means ofan axial passageway 112, while the inlet 108 of the pressure regulatingdevice 92 is connected to the radial passageway 82 extending through thewafer plate 14 by means of an axial passageway 114. The bore 94 in whichthe aneroid 100 is disposed is likewise in fluid communication with theradial passageway 82 by means of a restricted passage 116 which extendsthrough the partition 105 that separates the bore 94 from the valveinlet 108. These connections are made clear by the diagrammaticrepresentation of FIG. 4.

In operation the inlet passageway 108 and the bore 94 are both filledwith fluid which is at the same pressure as the fluid transmitted fromthe first pumping chamber 72 to the second pumping chamber 86 via thepassageways 80, 82. Due to the normal biasing force of the compressibleaneroid 100, the valve member 102 is biased into engagement with thevalve seat 106 thus preventing fluid communication between the inlet 108and the outlet 110 of the pressure regulating device 92. When pressurein the passageways 80, 82 exceeds a predetermined constant value due topressure pulsations or to a buildup of excess liquid at the outlet ofthe first pumping means as caused by the fact that the first pumpingmeans has a greater pumping capacity than the second pumping means, theexcess pressure is sensed through the restricted passageway 116, causingthe aneroid to contract while at the same time lifting the valve member102 off the valve seat and thus establishing fluid communication betweenthe valve inlet 108 and outlet 110 to permit the excess liquid to bereturned through the passageway 112 to the inlet side of the pump.

Aneroid 100 is designed to regulate the pressure at the inlet to thesecond pumping means to a predetermined constant value with the valuebeing sufficient to maintain the fuel in a liquid form. Thus, the netresult of utilizing a first pumping means of a greater capacity thannecessary, pressurizing the area between the outlet of the first pumpingmeans and the inlet of the second pumping means and returning excessfuel to the inlet of the device is to provide a fuel pump in which I theproblems generally produced by vaporization of the fuel have beensubstantially reduced. The pressure regulation which will be achievedwill depend upon the amount of bias of the aneroid 100, and the same maybe designed in a manner known to those skilled in the art. To facilitatemanual adjustment in the biasing force of the aneroid 100, the upper endas viewed in FIG. I is provided with a stem 20 extending externally ofthe end cover 18. The stem is provided with a threaded surface 122 whichengages a clockwise threaded surface 124 formed in the end cover 18. Byadjusting the stem, the amount of pre-compression applied to the aneroidand thus the amount of the pressure exerted against the valve member 102to seat the same may be varied. A cap 126 is provided over the stem 120to protect the same after it has been adjusted to the desired position.

It is apparent that a new pump has been described which is especiallysuitable for aircraft fuel pumps because of its solution to thevaporization problem inherent in such systems. It should be noted thatthe particular construction of this pump aids in this solution. Theproximity of the pumping means provided by the use of a single rotor andthe pressure regulating means within the same housing substantiallyreduces the possibility of pressure loss before the liquid reaches theinlet of the second pumping means and thus insures that the fuel will bein liquid form when received by the second pumping means.

Having thus described the invention, what is claimed is as follows:

1. A fuel pump for delivering liquid fuel to an engine comprising:

a housing having low and high pressure operating passages, one of whichis an inlet passage and the other an outlet passage;

means forming a cam surface in said housing;

a rotor rotatably mounted within said cam surface,

said rotor having a plurality of radial slots;

means forming a first and second chamber between the outer periphery ofsaid rotor and said cam surface;

means respectively connecting said inlet and outlet passages to saidfirst and saidsecond chambers;

first means reciprocably mounted in at least some of said slots andengaging said cam surface for displacing fluid through said firstchamber to form a first pumping means;

passageway connecting said first chamber to said second chamber;

second means reciprocably mounted in at least some of said slots andengaging said cam surface for displacing fluid through said secondchamber to form a second pumping means and whereby a single liquid flowpath is defined from said inlet passage through said chambers of saidfirst and second pumping means to said outlet passage;

said first pumping means comprising an axial portion of said rotorgreater than said second pumping means so that the pumping capacity ofthe first pumping means is greater than the pumping capacity of saidsecond pumping means whereby fuel is de-livered from said first pumpingmeans in an amount and at a pressure in excess of that required forpumping by said second pumping means; and

means carried in said housing intermediate said first and secondchambers and communicating with said passageway connecting said firstand second chambers for regulating the pressure delivered to said secondchamber to a predetermined constant pressure value to insure that thefuel delivered by the second pumping means will be substantially vaporfree and for returning excess liquid from the outlet of said firstpumping means to the inlet of said first pumping means.

2. The fuel pump as defined in Claim 1, and in which said last-mentionedmeans includes a conduit formed in said housing for returning excessliquid delivered to the passageway to said inlet passage of said device.

3. The fuel pump as defined in claim 1, wherein said cam surface meanscomprises a pair of cam tracks having wall means carried between saidcam tracks, said wall means extending from the outer periphery of saidrotor to separate said first chamber from said second chamber.

4. The fuel pump as defined in claim 3, wherein said first meansreciprocably mounted in said rotor slots comprises slidably mountedfirst vanes, the outer ends of said first vanes engaging the cam trackassociated with said first inlet and outlet zones; said second meansreciprocably mounted in said slots comprising slidably mounted secondvanes the outer ends of said second vanes engaging the cam trackassociated with said second inlet and outlet zones.

5. The fuel pump as defined in claim 1, wherein said last mentionedmeans further comprises:

a body having a valve inlet connected to said passageway and a valveoutlet;

a valve member normally closing communication between said valve inletand said valve outlet; and

means responsive to predetermined pressure increases in said passagemeans to open said valve inlet to said valve outlet.

6. The fuel pump as defined in claim 5, wherein said valve outlet isconnected to said inlet passage.

7. The fuel pump as defined in claim 6, wherein said means responsive tosaid predetermined pressure increases comprises a fluid tightcompressible member, one wall of which is connected to said valvemember, said valve member opening said valve inlet to said valve outletwhen said compressible member contracts due to said predeterminedpressure increase.

8 The invention as defined in claim 7 and in which said rotor, saidchambers, said cam surface, said pressure regulating means includingsaid compressible member, are all mounted in a single housing.

9. The fuel pump as defined in claim 7, including a restricted passageconnecting said passageway to the exterior of said compressible memberto compress the same in response to predetermined pressure increasestransmitted through said restricted passage.

10. The fuel pump as defined in claim 9, wherein said fluid tightcompressible member is an aneroid.

11. The fuel pump as defined in claim 10, including means forpre-compressing said aneroid to control the range of pressure increasesto which said aneroid is responsive.

' U N I TED' STATES PA'I ENT OFFICE. CERTIFICATE OF CORRECTION CMC-l576-A Inventor(s) I Hans U Bart "Itis certified that error appears inthe above-identified pateht fafid'tha-t s'aid Letters Patent are herebycorrected as shown below:-

7 Column :2, line 44, "part" should be path- Column 6," 1i ne'6l, change'de-livered" to --delivered-- 1 Sig ned a nd sealed this 2nd day ofJanuary 1973.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer r 1Commissioner of Patents

1. A fuel pump for delivering liquid fuel to an engine comprising: ahousing having low and high pressure operating passages, one of which isan inlet passage and the other an outlet passage; means forming a camsurface in said housing; a rotor rotatably mounted within said camsurface, said rotor having a plurality oF radial slots; means forming afirst and second chamber between the outer periphery of said rotor andsaid cam surface; means respectively connecting said inlet and outletpassages to said first and said second chambers; first meansreciprocably mounted in at least some of said slots and engaging saidcam surface for displacing fluid through said first chamber to form afirst pumping means; passageway connecting said first chamber to saidsecond chamber; second means reciprocably mounted in at least some ofsaid slots and engaging said cam surface for displacing fluid throughsaid second chamber to form a second pumping means and whereby a singleliquid flow path is defined from said inlet passage through saidchambers of said first and second pumping means to said outlet passage;said first pumping means comprising an axial portion of said rotorgreater than said second pumping means so that the pumping capacity ofthe first pumping means is greater than the pumping capacity of saidsecond pumping means whereby fuel is de-livered from said first pumpingmeans in an amount and at a pressure in excess of that required forpumping by said second pumping means; and means carried in said housingintermediate said first and second chambers and communicating with saidpassageway connecting said first and second chambers for regulating thepressure delivered to said second chamber to a predetermined constantpressure value to insure that the fuel delivered by the second pumpingmeans will be substantially vapor free and for returning excess liquidfrom the outlet of said first pumping means to the inlet of said firstpumping means.
 2. The fuel pump as defined in Claim 1, and in which saidlast-mentioned means includes a conduit formed in said housing forreturning excess liquid delivered to the passageway to said inletpassage of said device.
 3. The fuel pump as defined in claim 1, whereinsaid cam surface means comprises a pair of cam tracks having wall meanscarried between said cam tracks, said wall means extending from theouter periphery of said rotor to separate said first chamber from saidsecond chamber.
 4. The fuel pump as defined in claim 3, wherein saidfirst means reciprocably mounted in said rotor slots comprises slidablymounted first vanes, the outer ends of said first vanes engaging the camtrack associated with said first inlet and outlet zones; said secondmeans reciprocably mounted in said slots comprising slidably mountedsecond vanes the outer ends of said second vanes engaging the cam trackassociated with said second inlet and outlet zones.
 5. The fuel pump asdefined in claim 1, wherein said last mentioned means further comprises:a body having a valve inlet connected to said passageway and a valveoutlet; a valve member normally closing communication between said valveinlet and said valve outlet; and means responsive to predeterminedpressure increases in said passage means to open said valve inlet tosaid valve outlet.
 6. The fuel pump as defined in claim 5, wherein saidvalve outlet is connected to said inlet passage.
 7. The fuel pump asdefined in claim 6, wherein said means responsive to said predeterminedpressure increases comprises a fluid tight compressible member, one wallof which is connected to said valve member, said valve member openingsaid valve inlet to said valve outlet when said compressible membercontracts due to said predetermined pressure increase.
 8. The inventionas defined in claim 7 and in which said rotor, said chambers, said camsurface, said pressure regulating means including said compressiblemember, are all mounted in a single housing.
 9. The fuel pump as definedin claim 7, including a restricted passage connecting said passageway tothe exterior of said compressible member to compress the same inresponse to predetermined pressure increases transmitted through saidrestricted passage.
 10. The fuel pump as defined in claim 9, whereinsaid fluid tight compressible member is an aneroid.
 11. The fuel pump asdefined in claim 10, including means for pre-compressing said aneroid tocontrol the range of pressure increases to which said aneroid isresponsive.